I. Technical Field
The invention relates to a high-power electrode arrangement for furnaces. In particular, the invention relates to furnaces having at least one electrode embedded in the refractory material of the furnace lining.
II. Background Art
An exemplary electrode arrangement for arc or resistance smelting furnaces is disclosed in West German Patent DE-PS No. 31 06 741, wherein a base plate is arranged outside the brick lining of the furnace vessel, to which the necks of at least two rod-shaped, preferably straight electrodes are conductively connected. One end of the electrodes projects through the brick lining of the furnace vessel into contact with the melt contained in the furnace hearth. A cooling gas flow route is formed between the base plate and furnace vessel through which cooling gas is passed, preferably cooling air, to cool the electrode necks disposed on the outer side of the furnace vessel.
According to the arrangement of the electrodes disclosed in the above-identified patent, only the neck of the electrodes and the base regions of the furnaces immediately surrounding the electrodes are cooled. The proposed gaseous cooling medium is insufficient to cool the electrodes. The result is intense heating of the contact electrodes causing rapid degeneration of the electrodes. In use, the electrodes thermally expand because of the electric resistance heating and the heat conducted from the melt. Expansion of the electrodes causes stresses in the fire-proof material surrounding the electrodes which cause tension cracks.
An example of a furnace having water-cooled electrodes is disclosed in West German Patent DE-AS No. 1558 224 which discloses a furnace vessel having an electrode which projects from above the melt down into the melt. A disadvantage of this electrode arrangement is that it extends through the slag layer and is not protected by and embedded in the fire-proof lining, or refractory lining, of the furnace.
The invention is directed to the problem of providing an electrode which avoids the disadvantages noted above and is effectively cooled resulting in low wear and increased durability.